Infrared Photon Pair-Production in Ligand-Sensitized Lanthanide Nanocrystals

• Published in: Frontiers in chemistry 2020-11, Vol.8, p.579942-579942
• Main Authors: Agbo, Peter, Kanady, Jacob S, Abergel, Rebecca J
• Format: Article
• Language: English
• Subjects: Chemistry; downconversion; energy transfer; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; lanthanide; sensitization; two-photon
• ISSN: 2296-2646; 2296-2646
• DOI: 10.3389/fchem.2020.579942

This report details spectroscopic characterizations of rare-earth, core-shell nanoparticles decorated with the -element chelator 3,4,3-LI(1,2-HOPO). Evidence of photon downconversion is corroborated through detailed power dependence measurements, which suggest two-photon decay paths are active in these materials, albeit only representing a minority contribution of the sum luminescence, with emission being dominated by normal, Stokes' shifted fluorescence. Specifically, ultraviolet ligand photosensitization of Nd ions in a NaGdF host shell results in energy transfer to a Nd /Yb -doped NaGdF nanoparticle core. The population and subsequent decay of core, Yb states result in a spectral shift of 620 nm, manifested in a NIR emission displaying luminescence profiles diagnostic of Yb and Nd excited state decays. Emphasis is placed on the generality of this material architecture for realizing ligand-pumped, multi-photon downconversion, with the Nd /Yb system presented here functioning as a working prototype for a design principle that may be readily extended to other lanthanide pairs.